LAS VEGAS — When approached by a reporter early yesterday morning, Angel Heredia first had a question of his own. “Have you been writing good things about me or bad things?”

Heredia was joking, but it was a valid question considering his past and his work figures to come under even more scrutiny after Juan Manuel Marquez knocked out Manny Pacquiao Saturday night at the MGM Grand Garden Arena. HBO will replay the fight Saturday at 9:30 p.m.

Heredia is Marquez’s strength and conditioning coach. He also was a government witness at the infamous BALCO case involving Victor Conte. Heredia admitted he provided sprinter Marion Jones and other athletes with performance enhancing drugs.

Marquez never had dropped Pacquiao in any of their previous three fights. But in the second round, a right cross from Marquez put Pacquiao down and a devastating counter right hand with one second left in the sixth round knocked Pacquiao out cold. The Filipino superstar was coming on strong when Marquez avoided a punch and finished the fight. Pacquiao landed face-first and didn’t move for several seconds.

Yet, there were questions how Marquez at age 39 had the power to flatten Pacquiao for the first time in their four fights. Before the fight, Roach had questioned Marquez’s muscular build saying, “It doesn’t look natural.” But Heredia insists it was the science of combining strength training with nutrition and legal supplements.

“We trained for power, speed and explosiveness,” Heredia said. “A lot of people questioned whether Marquez would be fast on the night of the fight. But he was quick and fast and was able to get to Manny. He knew when to use his power at the right time.”

Heredia understands there will be whispers, especially considering his ties to the BALCO case.

“This is America. We all have the right to our opinions,” he said. “We have nothing to hide. We always wanted a blood test. The other people didn’t want it. I just hope the testing becomes neutral for everyone. Same methods and same testing for everyone.”

Roach didn’t point any fingers after the fight. There has been suspicion about Pacquiao who began his career at 106 pounds and maintained his power through eight weight divisions. It would seem a bit hypocritical to accuse Marquez of something after so vehemently defending Pacquiao.

“Things were said before the fight because of the tension,” Roach said. “But I have no problem with his camp.”

Each fighter underwent a urine test for steroids after the fight. Pacquiao was then taken to a hospital where a CT span showed no damage.

“I want to congratulate Juan Manuel,” said Pacquiao, who lost his second straight fight. “I have no excuses. It was a good fight and he deserved the victory.’’ I think boxing fans who watched us were winners, too.”

Pacquiao (54-5-2, 38 KOs) had said before the fight that he would continue his career. Marquez (55-6-1, 40 KOs) figures to do the same after savoring his victory. After a draw in the first fight in 2004, Pacquiao won two controversial decisions.

“I wanted the referee to raise my hand,” Marquez said. “I feel happy I left no doubt in this fight.”